In recent years, hybrid vehicles that use an engine and a motor in combination have rapidly become widely used to achieve higher fuel efficiency. On the other hand, marketing of electric vehicles that can run by a motor alone is in progress. To be feasible, these vehicles require use of a power converter for AC/DC conversion between a battery and the motor.
In the hybrid and electric vehicles, the semiconductor power converter is expected to be small and highly reliable. To this end, the power converter requires high cooling efficiency. As a measure to achieve this, a power converter structure of the double-sided cooling type has been proposed in which electrical conductors are connected individually to the obverse and reverse surfaces of a semiconductor element and heat is released from the electrical conductors to a cooler.
In assembling a power converter of the double-sided cooling type, joining work is required in at least two positions to join the semiconductor element and the electrical conductors on its opposite surfaces. Further, there is a problem that the number of assembly man-hours increases if joining of power terminals and signal terminals is taken into account. If the joining positions increase, moreover, the number of man-hours for the inspection of joint soundness increases, and assembly errors are accumulated so that finished-product dimensional stability is reduced.
A mounter is assumed to be used to enhance mass-productivity. In this case, parts may become misaligned due to shaky transportation or flow of melted connecting bodies, possibly reducing the assembly yield.